Mr 16 Years is continuing to steadily dig a PD grave for himself.
Start of last week he got called into HR for a meeting with the female head of HR about receiving a written warning for violating procedures (there's a very good reason we do things the way we do them, we've all been told plenty of times how to do it, and Mr 16 Years went ahead and ignored all of them). He responded by telling the head of HR that he would have to consult with his lawyer first because this was unfair and unprofessional of the company to do this to him. The head of HR apparently had had it with him and gave Mr 16 Years a darn good talking to, but since the head of HR is a woman, it was probably ignored.
End of last week, Mr 16 Years sent out a document for review. He had completely ignored all the precendents and guidelines for how the document should be formated. Basically we have a master document for each project, where all the necessary changes are listed so that we can keep track of all the changes. Mr 16 Years created an entirely new document in a completely different format, so basically if anyone wanted to review the changes for the project, Mr 16 Years' changes would be overlooked entirely because they're not in the main document. Another coworker (a male one, and one of the few Mr 16 Years would still talk to or take feedback from) had had enough of this and pointed out in a rather blunt email CC'd to a lot of other people that the correct procedure was [X] and by now Mr 16 Years should know how to do this properly.
Mr 16 Years accused male coworker of being "negative and unhelpful". It escalated into a verbal exchange where male coworker (usually very chilled out and very calm) finally finally lost his temper and responded to one excuse for not using the main document with "Bullpucky!" (although I mean the rude version, not the censored version I just typed). Mr 16 Years promptly emailed everyone documenting this as a hostile action and saying he was going to log a complaint with HR about this sort of abusive threatening behaviour.
Senior Analyst popped her head into the head of HR's office to warn her that there was probably going to be another complaint from "your favourite employee" about hostile workplace behaviour. Head of HR just sort of thumped her head on the desk and grumbled "Arrrgh".
Mr 16 Years didn't come to work the last two days (off sick apparently), conveniantly missing a prescheduled meeting for everyone reminding them "This is how we document changes". So now the meeting has been postponed until Mr 16 Years gets back, although we're now taking bets as to whether Mr 16 Years will somehow managed to "take lunch" during the meeting time and simply not pitch up for it. He's very good at missing "This is how we do things" meetings so he can claim he's never been told how to do XYZ so he's done it this totally unregulated way instead.